From around mid to late June, Kagawa's Sanuki Mannou Park celebrates early summer with their annual Ajisai Festival. The park grounds are home to around 200,000 hydrangea plants which encompass 40 different species, and they are one of the highlights of tsuyu, or the rainy season.
One of the fun things about this festival is that the park rents out traditional Japanese umbrellas (free of charge, too!), so that you can stroll around the park grounds and be elegantly protected from any incoming downpours.
Adult admission to the park is priced at 450 yen.